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FORTIFICATION 


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SXTRACTS OF LETTERS AND R=VIEVS.. 


From a Golonel of Engineers U, Se Army, 


"I have received the advance copy of your paper on "Fortification" and have | 
read it with a great deal of interest, I think you have covered the subject well 
and I congratulate you,” 


eu, 


from an Instructor U,S,Military Acadamy at West Point, 


"The object which you outline in your preface has been admirably accomplished 
and the subject handled in a thorough, unconventional and interesting way, The cuts 
are excellent," 


From a Major of imgineers U.S,Army, 


"You will see from the attached that your work on “Fortification” has been of 
assistance to the Board of ingineer Troops, 


Please accept my congratulations on the result you accomplished in pusting , 
_this subject_in a Shape which is different from the usual text-book style and, 
Which ‘it strikes me, will appeal to the military student,# 

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Fa 2 
. 


From a Major of Engineers U.S.Army, 


"The emphasis placed on concealment is not too strong, 
The artillery considerations are well stated, 
The Cavalry scope is set down simply and well, 
The discussion of overhead cover and splinter proofs is 
well done, and the information is Presh as applied 
to #uropean warfare," 


From a Major of zngineers U.S,Armny, 


"I congratulate you on having producec. an up-to-date treatment of the subject, 
The illustrations are well selected to bring out the important features." 


From an Officer — The Office of the Chief of Staff, 


"I congratulate you on what seems to me a very valuable condensation of 
up-to-date knowledge on the subject of fortification," 


From an Instructor of a Military Academy, 


"The advantage you take of the enormous development of trench warfare in 
Hurope makes your book the latest authority, besides which and most important 
it is written to read ~ not to solve," 


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— a 
yi Cara: 
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PREFACE 


Almost all military engineering work can be considered an aid 


to tactics. Fortification is one of the most important branches of 


military engineering and one of the most important aids to tactics. 
The civilian engineers of the nation can well take care of the con- 
struction, reconstruction, demolition and other engineering work in 
time of war, but they will not be of much help in fortification work 
unless they gain a knowledge of tactics. On the other hand, the 
militia officer with a knowledge of tactics must have some knowledge 
of the underlying principles of field fortification construction in 
order to use fortification to the fullest extent, and to the best advan- 
tage in solving tactical problems. 
The object of this short work on Fortification is: 


1. To impress upon the civilian engineer and the militia officer 
the importance of fortification. 


2. To show him how to analyze some of the problems and 
situations of field fortification. 


3. To give him some of the main underlying principles of 
field fortification. 


4. To create a desire for further study. 


5. To show the practical application of fortification in a 
modern war. | 


The author takes this opportunity to gratefully acknowledge the 
able assistance, advice and encouragement that he received from 
Major C. W. Otwell, Corps of Engineers, U. S. A., and from Major 
M. J. McDonough, Corps of Engineers, U. S. A. With the instruc- 
tions and assistance furnished by these very able officers, many of 
our militia engineers have gained a knowledge which will be of 
great value to our nation in time of war. 

In conjunction with this work on fortification the author recom- 
mends the following publications for study: 

Engineer Field Manual. 

Field Service Regulations. 

Infantry Drill Regulations. 

Cavalry Drill Regulations. 

Artillery Drill Regulations. 

Manual for Privates of Organized Militia. 

Technique of Modern Tactics (Bond & McDonough). 

Military Engineering (Beach). 

: Henry B. SAUERMAN, 
Captain Corps of Engineers, Illinois National Guard, 
Member American Society of. Civil Engineers, 
Member Western Society of Engineers. 


Presented at the Western Society of Engineers’ 
Meeting, May 1, 1916. 


Modern: Trench: Warfare. 2... s.. acc. s weiss 3 tne) eee 1 
Fortification.in Modern War?..2...0 45-5. 0b. 2s 2 5 
Field Fortification <<: sisie's aocie si ete’y « «ao > wo no 6 
The General’ Location-of Fortification’. .._.. >... 7 
The Division of the Fortification Into Sectors and the Garrison 

for Each Sectot:),cwiacceccuie ic, eg cee <istaiea ee 10 
The Division and Disposition of the Support and Reserve.... 11 
The Machine Guns sae Their. Disposition’. . 2 34 22.) eee 12 
The Artillery Position .::..5.....+0.+ 0.03 14 
The Disposition of the Cavalry... .. 25... 7s soe ie ee 16 
The Trench ‘Trace’and Profile. (7-0 7. 2 9 16 
Range. ‘Table :..:2 ag Sie +s tained ae ee 18 
Table of Penetration of the Rifle Bullet... .4 7 9a... 2a) ee 19 
Effect of Artillery Fire. .?. 05.555 7 sa. + pce ee eee 19 
Overhead: Cover: 2 a). sii oP a ei oe Zi 
| Doe) 5) se) (are Err UOT 22 
Drainage 9, 1.000.200 Te oe ee ed 
Artificial Concealment .. 04: <5... sste ul mee anes oe 23 
Clearing the’ Ground .* 0. os pe Res 23 
(Ahstacies 4. Riese eee ae vs doe eo k dus ve Inillgllt 50's he een gaan 24 
Dummy Trenchés 6.02. Oia. . v.00 -. se atges eee , et 
Execution of the Work... ....4.... 020.0...) ee 25 
Table of Hourly Working Capacity. Lous nies se 26 
Observation, Telephone, Water Supply and Magazines........ 27:3 
A. German. Fortified Position)... ..02.%22s-0. ss sen 28 
British: Trenches... 2. 2 ee 6 ol eee i eieven toate Mies. 28 
Permanent Hortificationi 9... 24am ee: beeen eee eee e eee eees 32 


Sea-Coast Fortification”... oe a ae ve 36 


FORTIFICATION 


By Capt. H. B. SAUERMAN, M. wW. S. E. 


MODERN TRENCH WARFARE, 


The modern rifle, the machine gun, the howitzer and the new 
field gun are responsible for the modern trench warfare. These 
powerful weapons make it impossible for troops to give battle in the 
open field without suffering tremendous losses. Cover and conceal- 
ment, either natural or artificial, are two of the main requirements 
of a modern battlefield. 

Trench warfare has brought out no new developments. Ad- 
vancing by sapping and parallels, mining and the use of hand 
grenades has not changed in principle; the application, however, has 
been more extensive with modifications to meet the new conditions 
and the more powerful weapons. 

Trench warfare is generally divided into four stages: 

1. The first stage is that in which the two armies come in 
touch with each other and after finding the open attack impossible, 
finally intrench. At this stage one army may take the defensive and 
the other army the offensive, or each army may attempt to attack 
the other. 

2. In the second stage they attempt to capture each other’s 
trenches. To accomplish this, attacks are carried on over the open 
space between trenches and if these fail each army advances by 
moving forward at night and by intrenching in the new position. 

3. In the third stage the armies advance upon each other 
mostly by digging trenches to the front. This method of advancing 
is called sapping and the trenches leading forward, usually in zig- 
zag fashion, are called saps. The heads of these saps are connected 
by trenches parallel to the original front or trench. Attacks in the 
open are also attempted at this stage. | 

4. In the fourth stage the trenches of these armies have come 
so near to each other that they can no longer advance by sapping. 
The advance by this method is stopped by the use of hand grenades 
and bombs which each army, without leaving the cover of its own 


1 


trenches, can throw into the trenches of the other army. At this 
stage the tunneling is carried out underneath the ground, the 
trenches are blown up and the craters caused by the explosion are 
occupied and are put in defensive condition by the army capturing 
them. 

To illustrate this system of warfare, plate 1 has been pre- 
pared. In order to explain this system we assume that a Red force 
is invading the territory of a Blue force. The Blue force is en- 
camped at the foot of Blue Hill and the Red invasion will proceed 
over Red Hill. When the Red advance guard reaches the crest of 
Red Hill it at once sends a message back to its commander advising 
him of the presence of the Blue force. The Red commander orders 
skirmishers to take position at foot of Red Hill and open an attack 
on the Blue Force. The Blue force answers with a vigorous in- 
fantry fire and as the Red commander sees the firing line of the 
Blue force receive heavy reinforcements, he at once decides to bring 


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Fig. 1. 


his artillery into action to support the infantry fire. His batteries 
are placed in rear of crest of Red Hill so that they cannot be lo- 
cated from Blue Hill and opens fire on the Blue force wherever 
they appear in masses. When the Red artillery is put into action 
the commander of the Blue force brings his artillery up near the 
rear crest of Blue Hill and attempts to silence the artillery of the 
Red force by bringing his artillery fire to bear on the Red artillery. 
The Red artillery changes its fire and attempts to silence the artil- 
lery of the Blue force. 

Attempts are now made by both infantry forces to advance and 
gain ground by rushes, but they find that their losses are consider- 
able, as both forces bring a heavy infantry and machine gun fire on 


2 


any section that rises and attempts to move forward. After several 
unsuccessful attempts the men throw themselves on the ground and 
place their knapsacks or blanket rolls in front of them and continue 
firing. While some of the men are firing others unstrap their in- 
trenching tools and start digging a shallow trench, throwing the 
earth in front of them for protection. Each man digs for a while 
and then fires at the enemy while his nearest neighbor digs. Mean- 
while the artillery duel continues. 

When night and darkness come both forces work with large 
intrenching tools. The Red force intrenches in position “X.” They 
dig a firing trench and another trench 50 yards in rear of the firing 
trench. In this rear trench they also construct bomb proofs. The 
two trenches are connected by zig-zag approaches. The Blue force 
constructs similar trenches, but the distance between their trenches 
is 75 yards. In digging these trenches concealment is given the 
greatest consideration. The omission of the parapet entirely or 
very low parapets with the sod placed back on the face toward the 
enemy is common practice. Dummy trenches, made from the exca- 
vated earth, are used to deceive the enemy. 

When daylight comes the artillery promptly opens fire on the 
trenches and the infantry forces take to cover in the bomb proofs. 
Only a small trench guard remains in the firing trenches. The men 
occupy themselves during the day, strengthening and improving 
their respective entrenchments. The machine guns are usually 
placed slightly in rear of the intervals between trenches and on the 
flanks. They are almost always masked and under cover so as not 
to attract the hostile artillery fire. 

The second night the Blue force sends out skirmishers about 
500 yards in advance of their position. The Red commander de- 
cides not to advance until heavy reinforcements arrive. 

To avoid a surprise attack he sends out small reconnoitering 
parties, who discover the Blue skirmishers about 300 yards from 
their trenches. They open fire on the skirmishers at once and are 
reinforced by additional men from the firing trenches. This inter- 
mittent fire is kept up the entire night. The Red force finds it to 
their advantage to advance their line 75 yards and to convert the 
first firing trench into a support trench with bomb-proofs, as shown 
at “Y.” The Red force also constructs wire entanglements in front 
of their position. 

The Blue force constructs a second line of trenches at position 
“B,” about 400 yards in advance of their first position. ; 

At daybreaek both forces start strengthening and improving 
their positions. Both positions are bombarded intermittently dur- 
ing the day. The Blue artillery brings a heavy fire on the wire 
entanglements of the Red force with the intention of destroying 
them. The Blue infantry force takes advantage of all possible 
means to advance their positions and, therefore, start sapping oper- 
- ations, which they find necessary, being in close range of the Red 
infantry fire. Several hours before dusk the Blue artillery opens 


3 


a heavy fire with high explosive shells. This fire is a steady fire 
directed on the Red trenches and wire entanglements. When dark- 
ness sets in this fire ceases. 

Shortly after dark the trench guards of the Red force hear 
noises made by the Blue force cutting the wire entanglements. ‘The 
Red force at once opens fire. The Blue force rushes forward with 
fixed bayonets. Many are shot down as they come up to the Red 
trenches. A portion of the Blue force finally succeeds in captur- 
ing a section of the Red trench, but their success is of short dura- 
tion. ‘The Red support is brought up and a machine gun on the 
flank of this captured trench brings a terrific fire into this trench. 
The men of the Blue force, who are not killed or wounded in this 
trench, escape in the darkness. Silence reigns for the rest of the 
night. In the morning it is found that the Blue force has con- 
structed another set of parallel trenches at position “C.” They have 
also connected these trenches to the saps which were started the 
preceding day by regular approaches. 

The artillery cannot fire on the trenches now as the two forces 
are too close and the danger of hitting their own forces is very 
great. The Blue force now starts sapping operations and continues 
to a short a distance from outside of the range of hand grenades 
and bombs. At the head of these saps small parallels are dug. The 
top of these parallels are covered over with logs and earth and a 
small steel shield with loop holes is placed in front of them. Sharp- 
shooters placed in these parallels act as a guard and shoot at any 
Red man who dares bring his head above the trenches. 

From these parallels the Blue force starts a tunnel, digging 
forward and gradually downward. This tunnel is about 4 ft. 6 in. 
high by 3 ft. 6 in. wide. When a depth of 15 ft. is reached the tun- 
nel is continued on a level. When the tunnel has passed under- 
neath the barbed wire entanglements, small branches are run to 
right and left of main tunnel. - These branches are madeugeen 
6 in. by 2 ft. 6 in. The smaller the tunnel the less) noisemind 
the quicker completed. When under the Red trenches a large 
earth auger (consisting of a heavy bar and large gimlet) is used 
to dig holes for the mines. Melinite is then placed in these holes 
and the Red trench is blown. This is usually done at night. Imme- 
diately when the trench is blown the Blue forces rush forward, the 
Red forces fire illuminating shells, when the Blue force rushes into 
the craters made by the explosion. The Blue engineers with picks 
and shovels and revetment, construct a parapet and also construct 
approaches back to their position. The ends of crater are blocked 
as only part of trenches are captured. 

The Red force, after recovering from the shock, comes to each 
side of trench occupied by Blue force with the object to recapture 
same. They are met with a heavy rifle and machine gun fire and are © 
forced to withdraw. The Blue force will then attempt to capture 
the balance of the Red trenches by sapping and mining as described 
above. The Red force will countermine and endeavor to drive out 


‘f 


the enemy and thus the struggle continues until one force or the 
other are practically exhausted and are driven or blown out of 
the trenches. 

The hand grenades used in this warfare consist of hollow recep- 
tacles filled with high explosives. There are two types: the per- 
cussion type, which has a fuse arranged to explode the charge when 
it strikes an object. The other type has a time fuse which is lighted 
before grenade is thrown. 

A small mortar is also employed, which is aimed almost straight 
in the air and will drop the small shell or bomb almost vertical into 
the enemy’s trench. 

For sapping the German army has now devised a digging or 
boring machine, with which they are able to accomplish the sapping 
operation in a very short space of time. 

Plate 2 shows a detailed sketch of the tunneling and mining 
operation. ‘This sketch is very clear and requires no further 
explanation. 








SAND BAGS 
PLAN 





SAND BAG METHOD 


DOE TAILS OF SAPPING & MINING OPERATION 


HB S4uerran 


Fig. 2. 


FORTIFICATION IN MODERN WAR. 


The extensive use of trenches and field fortification during the 
Russian-Japanese War and the great European War proves con- 
clusively that the proper and intelligent use of trenches and field 
fortifications, both for defensive and offensive operations, will have 
a most important bearing on the results of a modern battle. 

It may be accepted as a principle, established by experience, 
that a line of men can not remain stationary under fire without 
cover, natural or artificial. This is true in every phase of action, 
whether advancing, retreating, or standing on the defensive. Cover 
at all’times is desirable ; on the move it may be dispensed with, at a 
hait never. In some cases the cover will be partly natural and 


5 


partly artificial, i. e., partial natural cover artificially improved. In 
a majority of cases, however, conditions of fire efficiency and con- 
cealment will require a line to be placed where it could not possibly 
live without artificial cover. Another principle, which may be ac- 
cepted, is that on the offensive the line must determine the general 
position of the cover and not the cover the position of the line. The 
position of the line at any moment of a battle depends on tactical con- 
siderations and the progress and incidents of the fight. To prepare 
trenches in advance, except for defensive occupation, is to attempt 
to predict the future. It follows that all troops, not in a defensive 
attitude, must prepare their own cover after occupying a line or 
after they are halted. The importance is paramount of having 
available for instant use on every firing line the appliances and 
training to enable the men to get stifficient cover in the shortest 
possible time. This involves not alone the training of the men to 
dig with the tools provided, but also the knowledge and skill of 
their own officers to locate the trenches to the best advantage. 
There is no time to wait for instructions or advice from the outside. 

Permanent fortifications have an inestimable value as a refuge 
for a defeated army to rally under, as a defense to communications, 
as a protection to the flank of an army, as a protection of a frontier, 
and as a threat on the flank or rear of an advancing foe. 

Sea coast fortifications have a.great value in protecting sea 
coast cities, harbors, naval bases and other strategic points along 
the sea coast. 


FIELD FORTIFICATION. 


Field fortification is an aid to tactics and it should be con- 
stantly borne in mind that fortifications are designed for tactics, not 
tactics for fortifications. A thorough study of the general tactical 
situation is the first and most important step toward a successful 
application of fortification. The following questions will arise in 
the study of the situation: 

1. What is the general plan of operation? 

2. What part are the fortifications to take in the general plan 
of operation ? 

3. Will the fortification be used for defensive operation only? 

4. Will the fortification be used for offensive operation only ? 

5. Will the fortification be used for combined offensive and 
defensive operations? 

6. What will be the strength of the attack infantry, cavalry 
and artillery? 

7. What light arms, equipment, machine guns and artillery 
will probably be ‘used by the. enemy ¢ 

8. From what direction is the attack expected? 

9. At what time is the attack expected? : 

10. What are the natural features of the ground at- place 
where attack will take place? 


11. What is the available armament and available strength of 
garrison for the fortification? 

12. What are the available lines of retreat to a new position 
should the enemy’s attack be successful? 

It will not be possible to obtain all of the information as out- 
lined above. Information relative to the strength and armament of 
the enemy, time and place of attack, etc., will in many cases be 
very vague and unreliable. All available means must be used to 
secure as much information and as reliable information as can pos- 
sibly be secured. ‘The time for securing information will usually 
be very short, and for this reason the judgment and reasoning power 
of the officer must be used to the fullest extent in determining 
many facts. 

The work of Field Fortification may be divided as follows: 


1. The general location of the fortification. 
2. he division of the fortification into sectors and the garri- 
son for each sector. 
3. The division and disposition of the support and reserve. 
4. The machine guns and their disposition. 
5. The artillery position. 
6. The disposition of the cavalry. 
7. The trench'trace and profile. 
8. The overhead cover. 
9. Loop holes. 
mi. Drainage, 
11. Artificial concealment. 
12. Clearing the ground. 
13. Obstacles. 
14. Dummy trenches. 
15. Execution of work. 
16. Observation, telephone and water supply. 


THE GENERAL LOCATION OF FORTIFICATION. 


The requirements of a well fortified position are: 
Concealment. 


Good field of fire. 
Natural or artificial cover. 
Obstacles for retarding’ or directing the course of enemy. 
Easy and concealed communications for tactical move- 
ments of your troops. 
6. Obstructed and unprotected communications for enemy. 
7. Easy digging soil; free from rocks and roots. 
8. Sufficient height to give good view over ground over which 
enemy will advance. 
9. Nattiral flank protection. | 
Concealment is of the greatest importance. This does not 
only include the trench and parapet, but also the obstacles in front 
of same, for if these are not concealed they will assist the enemy in 


7 


ae taal a 


locating the trenches in rear and the hostile artillery will further 
destroy same. Formerly the field of fire was given the greatest con- 
sideration. The war of today has demonstrated that a field of fire 
of 100 yards will be sufficient if it can not be extended without loss 
of concealment. Low parapets, the omission of parapets, a back- 
ground, avoidance of sky-lines, narrow trenches, covered trenches, 
rounded crests and corners and the concealment of disturbed soil 
are all very effective in securing concealment. 

For concealment against observation from aeroplanes and also 
horizontal concealment, the author suggests a canvas covered trench. 
The canvas can be painted any color to suit the surroundings, or by 





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CANVAS COVERED POUBLE NER 
FikinG TRENCH : ay FuRiInG TRENCH 





Kige 3) 


scattering lightly grass, earth or other matter over the canvas almost 
perfect concealment can be obtained within a short space of time. 
The canvas covering will further protect the garrison from rain and 
the direct rays of the sun. Figure 1 on Plate 3 shows an ordinary 
firing trench provided with the canvas cover, as suggested by the 
author. Figure 2 shows a double tier firing trench provided with 
this same covering. ) 


The field of fire must permit of the full use of the defenders’ 
weapons. This requires a level or slightly sloping open space in 
front of the trenches for 100 to 700 yards. A grazing or parallel to 
the ground fire is the most effective. Fire delivered at a consider- 
able angle with the line of trench is not very accurate. The limiting 
angle for good results is about 12 degrees. Trenches should, there- 
fore, be fairly straight and at right angles to the fire. 

Cover, either natural or artificial, is essential for the protection 
against infantry or artillery fire. Natural cover is usually obtained 
behind crests of hills, in ravines, dry river beds, etc. Artificial 
cover is usually obtained in sunken roads, behind road and railroad 
embankments and in dry ditches or special trenches. 

Obstacles for obstructing or directing the course of the enemy 
consist of marshes, rivers, valleys, cliffs, hedges and forests with 
heavy undergrowth. All these natural obstacles may force the 
enemy to attack only from one line and direction. ‘The defender 
will then have the advantage to concentrate his entire force and 
means at the point of attack and prepare the position in advance. 
Where the enemy can be forced to attack over a narrow well swept 
front, the attack (everything else being equal) is almost certain to 
fail. 

Easy and concealed communications can be obtained behind 
rising ground, through woods, through ravines, through large stand- 
ing corn, etc. High sites furnish better protection for communicat- 
ing trenches than do low sites, but this advantage of the high site is 
oft’times offset when the defenders are compelled to deliver an in- 
effectual plunging fire. Where natural concealment for communi- 
cations can not be obtained artificial zig-zag or traversed com- 
municating trenches must be built. Cover trenches for supports and 
reserves must be constructed in locations where the country is flat. 

Where it is possible, the enemy should be forced to attack over 
difficult ground, requiring crossing of streams, etc., and where he 
will be exposed as much as possible, where his fire can not be devel- 
oped and where his movements will be impeded. 

Easy digging soil, free from large stones and roots, is very 
desirable where the time is very limited for the construction of 
trenches. 

Authorities differ regarding the height of a position. It is 
desirable to have a certain‘ amount of command for a defensive 
position. This height need only be sufficient to give an unob- 
structed view over the ground in front. In flat open country this 
height may be very little. The slopes to the front should be gentle 
and evenly sloping. A strong defensive position is one where one 
or both flanks are protected against attack by natural or artificial 
obstacles—rivers, deep marshes, mountains, etc., form good natural 
obstacles for protection. 

It is very apparent that very rarely a position will be found 
which will meet all of the conditions and requirements as outlined, 


9 


but it is also very evident that the position which meets most of the 
conditions and requirements will be the most easy to defend. ‘The 
officer, should, therefore, carefully study his position accordingly, 
for upon the selection of the position may depend the results of the 
battle. 


THE DIVISION OF THE FORTIFICATION INTO SECTORS AND “PRE 
GARRISON FOR EACH SECTOR. 


Field fortification, for tactical and administrative reasons, - 
should be divided into independent sections of such size as can be 
well commanded by one man. 

Such a division is an aid to tactics in that it allows the tactical 
units with their supports, reserves, supply, etc., to be kept together, 
and the duty and responsibility of attending to the many details can 
easily be divided by the commander among the subordinate officers. 
It is very apparent that a better field control will result with such 
an arrangement, and it is also very evident that such a division will 


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Fig. 4. 


aid the administration and supply department in the same manner. 
To illustrate the arrangement of a modern field fortification sector, 
Plate 4 has been prepared. Briefly, the arrangement, as outlined, 
is as follows: Firing trenches are designed for full company units. 
A small trench guard is always stationed in the firing trenches. This 
may consist of one platoon or less in case of artillery bombardment. 
In case of threatened infantry attack the other platoons of each 
company which are stationed in the bomb-proofs are rushed for- 
ward through the communicating trenches and take their plane in 
the firing trench. 

When the entire first battalion is in the firing trench, the second 
battalion moves up into the support trench and in the bomb- proofs. 
These bomb-proofs are loop-holed to permit of firing to the front 
and flanks. In case of capture of the first firing trench, the first 
battalion will fall back to the support trench and there combine 


10 


with the second battalion to stop the enemy’s advance ; under normal 
conditions the second and third battallions remain under natural or 
artificial cover and occupy the trenches only when conditions re- 
quire it. When conditions require it the arrangement can be modi- 
fied so that two battalions can be placed in the firing trenches with 
only one battalion in reserve. The machine guns are placed ap- 
proximately as shown. In this location—they are in position to 
deliver a fire between the intervals of the firing trenches and they 
can also be rushed forward to deliver a flanking fire attack on the 
firing trench in case it is captured and occupied by the enemy. The 
machine guns can also be placed so as to protect the flanks of the 
outer firing trenches. All machine guns should be masked or con- 
cealed so as not to attract the hostile artillery fire. 


THE DIVISION AND DISPOSITION OF THE SUPPORT AND THE RESERVE. 


Major W. W. Harts, in his excellent work, “Notes on Field 
Fortification,’ in the Professional Memoirs, gives the following 
information regarding the garrison, support and reserve: 

“From one-quarter to one-half of the entire force should con- 
stitute the general reserve and the remainder be distributed in the 
various sections of the front as needed. In each section it is advo- 
cated that about one-quarter to one-half of the force assigned to it 
should constitute the section reserve, ‘and of. the troops remaining 
about one-half or two-thirds should be supports. About one-fourth 
to one-sixth only of the section’s force will actually be in the 
trenches before being attacked. It seems to be desirable to reduce 
the force of men actually in the trenches to the smallest number 
consistent with safety. No exact proportion of reserves and sup- 
ports can be given for all cases and the foregoing is only stated as a 
guide in forming one’s own decision, which must always depend on 


the conditions peculiar to the ground, including the shape of the 


front, whether straight or curved, the size of the garrison, the enter- 
prise of the enemy and the interior communications. 

“But room in the trenches must usually be made for all the 
troops in the section, including perhaps space for some of the gen- 
eral reserve, so there must be some calculation made as to how much 
trench must be built or how much front can be occupied. 

“Trenches must always be able to furnish enough aimed rifle 
fire to stop any ordinary infantry attack across the open space in 
front. It is plain that this will vary greatly in different terrain. 
One might suppose that the enormously increased power and rate 
of fire of the modern rifles had lessened the number of rifles neces- 
sary, and that the old rule of thumb of one man per pace of firing 
line is no longer required. Such density is no longer necessary, 
except perhaps for a short time for repelling assaults after the 
attacking troops have managed to bring a large force within close 
assaulting distance. At such times the maximum amount of fire 
possible is needed. Men can not use their rifles accurately if occupy- 
ing less space than one pace of the front. This may then be adopted 
as a maximum density required for any part of the front where a 

11 


close attack may be delivered. This assumes that a part of the 
general reserve is on the line. At other places less hard pressed 
more length of trench and less density will be possible. An English 
authority has even stated that one man to every eight or ten paces 
is enough to check any infantry assault on a well chosen position, 
or including reserves and supports from two to five paces per man. 
We may safely conclude that from 1 to 4 yards per man, including 
sectional reserves and supports, are limiting estimates depending 
largely on the ground. The density suggested in our field service 
regulations, including supports and local reserves, is one man per 
yard, giving a front of 750 yards for the battalion, including inter- 
vals of 100 yards between companies, 1,500 for the regiment, and 
4,500 for the brigade. The judgment of the officer as to the strength 
required will have to be exercised in each of the larger parts of the 
line in order to have it fairly balanced, increasing the density in 
some places and decreasing it in others.” 


THE MACHINE GUNS AND THEIR DISPOSITION. 


Machine guns are now recognized as one of the most potent 
factors in battlefield operations. Our Field Service Regulations, 
1914, Par. 34, gives us the following information: 


“Machine guns are emergency weapons. ‘They are best used 
when their fire is in'the nature of a surprise to the enemy at the 
crises of combat. Their effective use will be for short periods of 
time—at most but a few minutes—until silenced by the enemy. 
When engaged they must be used to the limit of their effective 
capacity. On the offensive they find their use in assisting the attack 
to obtain fire superiority temporarily lost and against lines of 
trenches which are to be assaulted. In the defensive they are used 
against large targets visible for a short time only, and on advancing 
lines of the enemy’s infantry within the short and mid ranges. The 
effect of the enemy’s fire, particularly his artillery fire, on machine 
vuns, is lessened by their employment in small groups.” 

In event of an assault they enable a heavy fire to be developed 
at a point where the enemy is strongest, provided the machine guns 
are placed so as to admit of their free use. For the defense of 
flanks of both infantry and artillery, for the defense of ditches, for 
positions where infantry would be visible or liable to enfilade fire, 
the machine gun posted behind natural cover or other concealment 
will give excellent service. Machine guns are placed between in- 
tervals of trenches as shown in Plate 4 and also on the flanks of 
infantry and artillery positions. They should be well concealed 
and the emplacement so constructed as to afford a maximum pro- 
tection to the gun detachment consistent with the free use of the 
weapon. Splinter-proof overhead cover is desirable and should be 
provided wherever possible. Shelter should.be provided for both 
gun and detachment when not engaged. It will sometimes be found 
to advantage to connect emplacements by communicating trenches. 


12 


Fig. 1, Plate 5, shows a Single Machine Gun Emplacement. Fig. 2 
shows a Double Machine Gun Emplacement. 

Lieutenant Henry J. Reilly gives the following report regarding 
the value of machine guns in the present European war: 

It is particularly in the defense of an intrenched position that 
machine guns are useful. Here, as in a fight in the open field, they 
must not open fire too soon, or the hostile artillery will wipe them 
out. Therefore, they generally remain silent until the enemy’s 
infantry comes out of its trenches and starts across the intervening 
space in its endeavor to capture its opponents’ trenches. Then the 
machine guns open fire and keep it up until the last of the enemy 
left alive or unwounded have run back into their own trench or 
until captured or put out of action by a hand grenade if the attack 
is a success. 

The Germans frequently arrange their trenches so that if 
occupied by the enemy a machine gun can fire down them, thus 
enfilading him and driving him out. If the configuration of the 






ES ‘oe 184 
-40 ‘ 
SECTION C-O “L 
See SECTION A-B 





s., 
bed Ont 







=3'0 
SECTION A-B SECTION A-B SECTION C-D 





EMPLACEMENT FOR EMPLACEMENT FOR GUN Pit 


i! 2-MACHINE GUNS TOTAL EXCAVATION $30 CUFT 
: MACHINE GUN TIME TO CONSTRUCT SEMEN 2TOGHRS TIME To CONSTRUCT I2MEN 1-2HRS 
*. Fia.l Frie.2 Fia.3 
. 
igi ay 


ground will permit it, they place most of their machine guns, not 
in the first line of trench, but in some position back of it. This is 
done to avoid probable destruction by the heavy shelling to which 
a trench is subjected by the enemy’s artillery before an attack is 
made. 
3 In accordance with this principle, where the Germans have been 
able to prepare a position ahead of time, they pick out a gentle slope 
and put three lines of trenches on it. The machine guns are placed 
in the last line, thus being able to shoot not only over the first two 
lines at any approaching enemy, but making a strong third line very 
difficult to capture, even though the first two lines are captured. Also 
until this third line is captured and a hole thus broken entirely 
through the position, little is gained by the capture of the first two 
lines. 

Frequently in Poland there have been large stretches of country 
where the invaders have had no other desire than to remain on the 
defensive. In these stretches the Germans strongly intrenched and 


13 


garrisoned the important points. Between these points they con- 
structed several lines of trenches, each with a very wide barb wire 
entanglement in front. 

These trenches would have comparatively few troops in them, 
but a considerable number of machine guns. While a Russian attack 
might succeed in breaking through most of the entanglements in 
spite of the machine gun fire, it would take them so long that the 
German reserves from central points in the rear of the line would 
have ample time to get up. 


THE ARTILLERY POSITION. 


The artillery position is usually selected by the chief artillery 


officer after he learns the general situation and requirements from 
the commander. 


Artillery positions are generally in rear of the intrenched — 


infantry positions and are concealed from view usually by natural 
cover. When conditions permit, the artillery should be placed in a 
somewhat commanding position. Due to the perfection in firing 
by indirect laying, guns are now usually placed in rear of the crest 
of the hills. The advantage of such a position is easy concealment 
and easy concealed withdrawal, both of which are more important 
than direct fire. Concealment and mobility are in fact the most 
important factors. Dispersion is very necessary to reduce the hits 
of the hostile artillery, and with the improved field telephone sys- 
tem, guns can be scattered over a wide area without the loss of 
control. There should be numerous alternate emplacements, with 
casemates for the protection of the men. This will allow changes 
of position with a minimum loss of time. Positions should be 
selected to furnish a concentrated cross fire on all possible lines of 
advance of the enemy. Whether the heavy guns should be placed 
to the front or to the rear depends very much upon the enemy’s 
armament; if he has only the small caliber guns, the large guns 
may be kept in the rear; if the enemy has large caliber guns it will 
be necessary to place the heavy guns to the front to prevent him 
from building his batteries. 

Good sites for observation stations are a prime necessity.” They 
should be well concealed and connected by telephone to the different 
battery commander stations. Where it is possible, emplacements 
should be connected by concealed approaches. 


The light field guns, which in practically all armies are about - 


three-inch, are generally found in the zone from 2,000 to 4,000 yards 
from the enemy’s trenches. The heaviest guns, such as the 305 
millimeter (about twelve-inch) howitzer, are found at from 6,000 
to 8,000, or even more, yards from the enemy’s trenches. 

The guns of the intermediate caliber, such as ten-inch howitzers 
and fifteen centimeter-rifles, are found somewhere between the light 
field guns and the heaviest ones. 

The Austro-Hungarian 305-millimeter howitzer has been ex- 


tremely efficient thorughout the war. A large part of the work | 


14 


credited by the allies to the 420 millimeter has in reality been done 
by the 305. One of the marked features of this gun is its mobility. 

The gun, the carriage in two parts, and a steel platform on 
which the gun and carriage rest during firing, travel on four steel 
trucks with heavy wheels, which are pulled by one or more traction 
engines, depending upon the state of the roads. 

When the firing position is reached, the ground is leveled, the 
steel platform put down, and the gun and carriage mounted on it. 

The 3-inch field gun, the 6-inch long range heavy guns and the 
5-inch howitzer and mortar are usually employed in the field fortifi- 
cation. 

The mortars and howitzers are usually located in retired posi- 
tion on the reverse side of hills, in ravines, etc. 

In addition to the heavier guns, the 1-pound automatic and the 
3-pounder and 6-pounder rapid fire guns are employed to good 


FIELD HOWITZER Of @iEGE GYR «| 
q Y 





. ew , 

‘ : : \ 

Winn, BAZ 

edt] H 

af vc H 

en’ pe aie } 

0) Eye _ the — —Uet 

ALF on - 

Je 


INFANTRY TRENCHES 


wir 
EN TAN@LEMENT 


REAR ELEVATION 


FORTIFIED ARTILLERY POSITION 





Fig. 6. 


advantage. In case of assault they will bring a heavy fire to bear 
on the enemy. 

Fig. 3, Plate 5, shows a very simple and easily constructed gun 
pit. The pit can easily be modified to meet different conditions and 
the low parapet admits of easy concealment. It was used extensively 
by the Russians in the Japanese War. 

Plate No. 6 shows a fortified artillery position on the front 
slope of a hill. Such a position ds a difficult one to conceal and 
further makes it very difficult to change position without being 
observed by the enemy. Brush, canvas, trees, sunken roads and dry 
ditches will oft’times help to overcome these disadvantages. It will 
be noted that the guns shown in this plate are all firing over the 
infantry trenches. This is a very common practice in the present 


15 


European War. ‘The guns should be placed at least 600 yards in 
rear of the infantry position so as to protect the artillery position 
from flank and rear attacks and further not expose the infantry to 
loss from premature bursts. For the sake of showing the gun posi- 
tions clearly, they are all shown in cross section. In actual practice 
these guns would not be placed one directly in rear of the other, but 
would be widely scattered. 


THE DISPOSITION OF THE CAVALRY. 


Cavalry can render valuable service in connection with field 
fortification by the performance of the following duties: 

1. Reconnoitering the enemy’s position and securing informa- 
tion as to his strength, armament, disposition of troops, etc. 

2. Delaying the enemy’s advance so as to give the troops 
sufficient time to dig their trenches. 

3. Selecting and holding strong defensive positions in advance 
of the infantry. 

4. Protecting the flanks of a fortified position. 

5. Threatening the flanks of the enemy and forcing him to 
attack along certain lines. 

6. Clearing the ground by tramping down crops, such as 
standing corn, etc. 

7. Performing demolition work. 

Cavalry in modern war will seldom be called upon to make 
mounted charges. It has the great advantage of mobility. Infantry 
carried by motor trucks does not have the mobility that cavalry 
has, because the trucks are confined to good roads and also on 
account of the small number of trucks available. 

The cavalry in the present European War is mostly employed 
in seizing strong position in advance of the infantry and holding 
these position by fighting dismounted until the infantry arrives. 
When the Allies were trying to extend their lines to Antwerp and 
the Germans were trying to reach the Belgian coast in October, 
1914, the cavalry of both armies played a most important part in 
the region of Lille and Ypres. 

Cavalry played a most important part in the Allies’ retreat and 
the German’s advance to the Marne. , 

Cavalry is also employed in filling gaps between infantry units. 
Owing to its great mobility, it can reach decisive points long before 
it would be possible for infantry to do so. The present war shows 
many instances in which cavalry filled important gaps. 


THE TRENCH TRACE AND PROFILE. 


Prepared fortified lines of resistance will consist normally of 
successive lines of trenches or supporting points with intervals, the 
intervals being such that mutual defense by cross fires and flanking 
fires is assured. The supporting points will usually be groups of 
rifle trenches combined with natural topographical features. The 


16 


intervals between trenches and Eee eaue points will vary from 100 
to 800 yards. 

The flanks of a trench or a position will always be tempting 
points for the enemy’s attacks and they should therefore be secured 
by resting them on impassable obstacles or, if this cannot be done, 
by echeloning them to the rear and placing reserve trenches close 
at hand. 

Long trenches are not desirable even where the ground permits 
of their application, which it ordinarily does not. Any long trench 
once located by the enemy easily leads to the disclosure of the 
remainder. A long trench penetrated at any point will generally 
become untenable. For these reasons it is considered preferable to 
limit the length of a single trench to that required for a company 
and if a greater development of fire is needed, additional trenches 
of company, platoon or even squad length may be constructed. The 
several trenches of a group need not and generally would not be 
on the one line, but might by separated in depth as well as laterally. 

The trace of a trench should follow a contour. Men standing 
about 11 paces apart may hold a tracing tape at the height of 
parapet. By looking all along the tape, it will be seen whether each 
part of the parapet will command the ground in front of it. If the 
command is greater than required, the parapet may be lowered or 
retired. Note also whether the longest trenches are on the sides 
of the easiest approach, if not trace must be modified. Fairly 
straight lines at right angles to the delivery of fire are to be pre- 
ferred. If curves must be introduced they should have a radius of 
at least 20 yards. All trenches should be long enough to give an 
effective volume of fire. A squad trench 11 paces or 9 yards is 
about the minimum. 

Tracing and profiling are not independent operations. The 
trace depends upon the profile and the profile upon the trace. The 
profile, however, is fairly well standardized while the trace must 
be determined by the circumstances and conditions. In field fortifi- 
cation the term trace usually designates the horizontal projection of 
the interior crest. This trace, as stated before, should follow a 
contour; if the contour curves, the trace should also curve; sharp 
angles should be rounded off so as to make them less conspicuous. 
Plate No. 7 shows a trace of a Battalion Supporting Point in accord- 
ance with the German Regulations 1910. 

Due to the improvements in rifle and artillery fire, the high 
parapets and broad trenches of the past years have been replaced 
with narrow trenches with very low parapets or with parapets 
entirely omitted. If a parapet is used, the crest should not be over 
18 inches above the ground and the surface should be a straight 
gentle slope, not steeper than 1 on 6. Both these conditions help 
considerably toward concealment. The front wall should be as 
near vertical as possible; this provides better shelter and helps the 
soldier when in firing position. An elbow rest of 9 to 12 inches is 
also an aid. Most authorities state that a height of 4 ft. 3 in. to 
4 ft. 6 in. from the bottom of the trench to the crest of parapet is 


17 


necessary for a man firing while standing. The author’s experience 
has been that 4 ft. 8 in. will better meet the average condition on 
account of the dirt along parapet being disturbed by movement of 
rifles, etc. Furthermore, in case of heavy rains the height of parapet 
will be reduced. Should this height be too great for certain soldiers 
it can readily be decreased by throwing a little of the dirt to one side. 
There is a practical limit to the narrowness of a trench. A 
trench narrower than 2 ft. can not be dug and used to good advan- 
tage. It is too narrow for two men to pass in it or for a man to 
sit with his back to the front wall; 3 ft. is the limit for this purpose. 
Major Harts gives the following essentials of the profile: 
First, a low bullet-proof parapet not over 18 inches high with 
a single gentle slope not steeper than 1 on 6 and an elbow rest 9 
inches below the crest; second, a narrow trench with vertical or 
nearly vertical sides and of sufficient height to cover a man standing, 


is Ot 


——__* 





TYPE © 
IDEAL BATTALION SUPPORTING PoinT. 
GERMAN REGULATIONS 1910 


APLATOONS IN TRENCHES 
bg * SUPPORT 
2 COMPANIES IN RESERVE 
TRENCH ROOM FOR ENTIRE BATTALION lYo FER MAN 
ABou T 400 YHDS LONG OVERHEARD COVER FoR 2 PLATOONS. 


Big. 


and wide enough to sit in and permit another to pass; third, some 
protection from enfilade or oblique fire by using traverses or special 
arrangement of the ground plan, and fourth, a bottom slope with a 
gutter for drainage. The following tables and information relative 
to range and penetration will assist in determining the necessary 
thickness of parapet: 





RANGE. 
Field Heavy 
Bales Rifle Artillery Artillery 
Yards Yards Yards 
Distantiine eee Over 2,000 Over 4,500 Over 6,500 
Tgviovusts omen 2.000 to 1,200 4,500 to 3,500 6,000 to 5,000 
Biectiverio maces 1,200 to 600 3,500 to 2,500 4,000 to 2,500 
Closew.. Wether an Under 600 Under 2,500 Under 2,500 


18 


PENETRATION OF RIFLE BULLET. 


ee 


Inches 
200 Yards ~ 600 Yards 
Rammercial Steel...........0....005 0.30 0.20 
One-inch broken stone, gravel....... 4.80 4,28 
Hard coal between 1-inch boards.... 9.00 7.00 
fericeemasonry; cement™............. 2.20 1.16 
Brcko masonry, lime*?....2..,...... 2.40 1.14 
EEN so ees ake et, We, 18.18 11.96 
Mamcrete, port, 1-3-5..0% wel. 2... ee. 3.00 1.86 
ASE ERE eae, ce een ae 26.46 12.46 
MIRE eg Sieagtth Dkls oss dos 30.00 13.00 
EI MR ey rn ie ita ts nie 25.72 13.00 
IITA TIT: 6 Sasso caida ee oe do's a, 30.00 16.12 
ES cs ee re ee 60.00 32.00 





EFFECT OF ARTILLERY, FIRE, 


Up to 3,000 yards, the 3-inch field gun, using high explosive 
shell, is effective against ordinary types of overhead cover for 
field trenches, brick buildings and stone walls 2 feet thick. It is 
ineffective against earthen parapets. 

The heavier. types of field guns and howitzers are effective 
against all kinds of field works, and protection against this kind of 
fire must be secured by concealment. 




















iene, : 
=F 
| d gy uy 
“A ar Fk eto 
| - Wo rs + 
dg a4 a Wl 
= ~ PH ae tie te Wer SF 
60 eT THe |p 
[| : Sof 
Segisy iy 
; ies, |b 
a co re 
al ‘ 


ec 





PROFILE OF FIELOWORKS 


Fig. 8. 


The thickness of ordinary earth required to resist penetration 
at usual battle ranges is 3 ft. for rifle fire, 10 to 24 ft. for field guns. 

Plate No. 8 shows a profile-of field works on which the names 
of the component parts are indicated. -Plate No. 9 shows our 
standard profiles as outlined in our Regulations. Plate No. 10 
shows a progressive trench profile adopted from German and English 
regulations. | tyme 


*For single shot. 
tIn sacks, about one-half these figures. 


19 


LSFT. COMMAND STANDING TRENCH 
ENLARGED 


TIME TO CONSTRUCT (SOFT GROUND) 2 TO +4HOURS 
PER YD OF LENGTH ae 


a 


ee ee 


L.SFT. COMMAND SPLINTER PROOF 


TIME TO CONSTRUCT(SOFT GROUND) 
2T0 4 HOURS PER YD. 


| rrr 
AREA 14,75 SQ.FT. 
an 


eee Lae af a: 


2FT. COMMAND STANDING TRENCH 


TIME TO CONSTRUCT (SOFT GROUND) 2TO4 WARS. 
PER YD. OF LENGTH 


+4.8.S. 





Fig. 9. 
20 


/ 


OVERHEAD COVER. 


Overhead cover should be provided wherever and whenever 
possible. This need not necessarily be of massive nature, but in 
many instances it need only be sufficient to give good concealment. 

Our Engineer Field Manual gives us the following information 
regarding thickness of overhead cover: 

For splinterproofs 6 to 8 inches of earth is necessary with a 
timber structure sufficient to carry the load. For bombproofs a 
minimum thickness of 6 inches of timber and 3 feet of earth is 
necessary against field and siege guns and 12 inches of timber and 
6 ft. of earth is necessary against howitzers and mortars of a 
heavy siege train. A German military engineer recommends a 
thickness of earth equal to twice the depth of penetration of the 
shell before bursting and a supporting structure of sufficient strength 
to safely carry from 2 to 4 times the weight of earth coming on 
same. 

Col. von Schwartz states that during the siege of Port Arthur 


PROGRESSIVE TRENCH 
ADAP TES FROM 


GERMAN & ENGLISH REGULATIONS 


Ce? lg ke 


CF) S04 Revatwenf 






Broan 


KNEELING TRENCH 
IST STAGE 1HR 





STANDING TRENCH 
S*° STAGE SGHRS-SVHRS 


KNEELING TRENCH 
WIDENED FOR PASSING 


STANDING TRENCH WITH OVERHEAD COVER 
ESS STAGE 2HRS 4TH STAGE GHRS-/JOHRS 


Fig. 10. 


a 5-ft. thickness of clay tamped in one-foot layers and placed over a 
concrete roof successfully withstood the repeated action of a 6-inch 
shell. For concrete covering Colonel von Schwartz recommends a 
thickness of 9 ft. to resist the 1l-inch shells, such as were used at 
Port Arthur. 

Our sea coast fortifications are provided with a 10-ft. Portland 
cement concrete overhead cover. 

An earth covering from 5 to 10 ft. in thickness placed over 
concrete roofs greatly assists in taking up the impact of the shell. 
_ The German practice in the present war is to provide dug-outs 
from 25 to 35 ft. below the surface and in front of their trenches. 
‘These dug-ouis are reached by half-galleries. Plate 11 shows two 
types oi these dug-outs with galleries for same. The British pro- 
vide recesses in their front trench walls, as shown in Plate 15. 


21 


LOOP HOLES. 


The use of loop holes must be determined by the local condi- 
tions. The chief disadvantages of the loop holes are the reduction 
of rifles and the restriction of the fire to a frontal direction. Visible 
loop holes are very dangerous and to aid concealment the rear of 
the loop hole should be shut off from any light. 

As concealment is one of the most important factors in trench 
warfare, the use of loop holes is very common in the present Euro- 
pean War. The most serviceable form of loop hole consists of a 
pyramidal box made of 2-inch plank with a steel plate spiked on 
small end of same and pierced for fire. The steel is % inch thick 
and the opening in same is about 2 inches by 4 inches. This open- 
ing is usually provided with a movable lid which closes the opening 
when not in use. This is known as the “hopper loop hole.” 


SANO BAGS 
= 










AccES8S THRY very 


~ 
Pe 4 
SLOPING HALF GALLERY ' 
| 4 i’ 


GERMAN DuG OUT OF THE 
PoRsTlLne. 






TY 






tte 
LTT 
= 







rr | 
osha 
I 


< 
7 





Aw) Thay) 
ee a ee 








1X) 

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of al 
w & 

oe ~ 4) 

oil 10g 

ati SECOND TYPE OF GERMAN 
DuG-OuTr 
FiG.2 





ig dd. 


Loop holes can also be readily constructed with sod or sand 
bags. 

Loop holes must not be closer than l-yard intervals. If placed | 
closer they will weaken the parapet. All loop holes must be masked 
so as to avoid discovery by the enemy. A continuous loop hole may — 
be readily constructed by placing two 14-inch diameter logs along 
and above the parapet with supports 14 feet apart. The logs raised 
from 3 to 6 inches above parapet so as to give the men sufficient 
space to fire through. Concealment can be secured by throwing 
grass or dirt over logs so as to blend with the surroundings. 


22 


DRAINAGE. 


The drainage of trenches is of great importance. When 
trenches are constructed under threatening weather conditions, or 
where trenches are constructed near the foot of a hill or in low 
level country, drainage becomes a prime necessity even if the 
trenches are to be occupied for only a comparatively short time. 

Trenches should at all times be made as dry as possible. The 
floor of the trench should be made to slope backward to a small 
drainage ditch or gutter which carries the water to a sump-or to a 
point where it can be disposed of otherwise. Hand-operated pumps 
or small power-driven pumps can oft’times be used to good advan- 
tage. Provisions should always be made for excluding surface 
drainage when constructing trenches on the side of a hill. Fascines 
laid on floor of trench will aid very much in keeping the feet dry. 
Nothing will take the fighting spirit out of a soldier quicker than 
will wet feet or wet lower garments. 


ARTIFICIAL CONCEALMENT. 


With the extensive use of the high power weapons and the 
howitzers of small and large caliber, the question of sufficient thick- 
ness for both horizontal and overhead cover becomes a serious and 
difficult one. The author fully agrees with the school of military 
engineers who believe that the best protection lies in concealment 
and mobility. Even if the protection by thickness of cover alone 
would be advisable at times, the element of available time will enter 
into the problem and in many cases will not permit the construction 
of sufficient thickness of cover. 

Low parapets, sodded parapets, the entire omission of parapets, 
avoidance of skyline, certain backgrounds, narrow trenches, curved 
traces and concealment of disturbed ground will aid greatly in 
securing concealment. Obstacles must also be concealed to avoid 
their destruction by the enemy’s artillery and further avoid aiding 
the enemy in locating the position by means of the obstacles. Light- 
ing systems should be of a flashing rather than of a constant nature. 

The author again wishes to bring the reader’s attention to his 
canvas system of concealment, as:shown on Plate 3, for infantry 
trenches, and on Plate 17, for permanent fortification. Canvas will 
not only offer good concealment by giving it the color of the-sur- 
roundings, but it will also furnish protection from the rays of the 
sun and from rain, sleet and snow. 

Even the armored turrets could be concealed to good advantage 
by means of this material. The canvas could be made up in rolls 
so that it could readily be handled by two.men. 


CLEARING THE GROUND. 


Clearing the ground to obtain a good field of fire should be 
given very careful consideration. A clear field of fire of 100 yards 
in front of the trenches will be sufficient if it cannot be extended 


23 


without loss of concealment. Large trees in standing position give 
less concealment than when lying on the ground. Thickets and 
brush can be cut down or burned. Large high-standing crops, such 
as corn, cane, etc., can readily be tramped down by cavalry or 
leveled with horses hitched to some kind of a drag. Special atten- 
tion should be given to objects which will afford probable conceal- 
ment for the enemy’s artillery or machine guns. These objects 
should be destroyed. If the sacrifice of labor and time is not too 
great and good concealment is not sacrificed, a field of fire of 800 
yards will oft’times be found of great advantage. 


OBSTACLES. 


Obstacles assist in strengthening defensive positions. 

Obstacles should form no shelter for the enemy. 

Obstacles should be sheltered from the enemy’s artlleme fire 
wherever possible. Obstacles should be difficult to remove. Obsta- 
cles should not interfere with counter attacks. 

Obstacles should be placed from 25 to 100 yards from the 
trench. 

Obstacles should be concealed. This can be accomplished by 
scattering small pieces of brush over same but this brush must not 
be of such density so as to afford a screen for the enemy. Another 
effective method is to provide a shallow wide trench for wire 
entanglements, etc. 

Col. Fiebeger, in his work on Fortification, gives us the follow- 
ing information relative to obstacles: 


“Obstacles are employed in connection with fortifications to 
protect the works from surprise, to break up the assailant’s forma- 
tions, and to hold his troops for a time under the accurate fire 
of the defender. They should be concealed from the assailant, they . 
should neither give him cover nor conceal his movements, and they 
should be difficult to destroy. Obstacles may be placed either in 
front of or along the line of defense. If in front of the line, they 
are most effective if they are under the close infantry fire of the- 
trenches, under close observation at night, near enough to the line 
of defense to compel the assailant to cease his artillery fire before 
his infantry reaches them, and far enough from that line to save 
them from destruction during the artillery bombardment which 
precedes the infantry attack. - Obstacles along the. line are either 
in the ditches of the fortifications or in the intervals between the 
works of the intrenched line. For passive defense the obstacles in 
front of a defensive line should be continuous; for active defense 
they are employed only in the defense of salients or key points.” 

Plate 12 shows different types of obstacles, including some of 
the latest types used by the German army. 


DUMMY TRENCHES. 


Dummy trenches are useful in diverting the enemy’s fire. These 
trenches are usually constructed with the waste ground from the 


24 


regular trenches or they are quickly constructed by means of horses 
and plow. The appearance of these dummy trenches must be of 
such appearance so as to deceive the enemy, otherwise it is very 
apparent that they will fail in their purpose. 


EXECUTION OF THE WORK. 


Fortification, like all other work, should be executed in the 
shortest possible time and with the least fatigue of the men. 

The officer must bear in mind that 2 hours of digging will leave 
a soldier fit for both fighting and marching, while 4 hours of con- 
tinuous digging will unfit him generally for either fighting or march- 
ing. | | 3? | 

In executing the work the first step is to mark on the ground 
the projection of the interior crest, sometimes called the firing 
crest. It may be marked continuously by stretching a line or by 


CEE SB A PS 


PROTECTED ENTANGLEMENT 





OBSTACLES 


Figs: 12: 


scratching the surface with a pick. The author suggests that a line. 
be stretched at a height of the interior crest supported on stakes set 
11 paces or approximately 9 yards apart. These stakes will mark 
the length of a squad trench with an allowance of 1% feet on each 
side for a traverse. The second step is to determine the depth and 
width of trench and to check the height of parapet so as to assure 
a clear field of fire. The third step is to mark the toe of parapet 
and also lay out the ditch if one is required. This is best accom- 
plished with stakes set about 2 yards apart. 

Working parties should be made up so far as possible of entire 
organizations. A battalion should be ordered to send one, two or 
three companies; a regiment, one or two battalions, and a brigade, 
one or two regiments. 

Work should be performed by complete units—this will greatly 


25 


assist in control and placing responsibility. The author believes the 
best results can be obtained by assigning one squad to each 9 yards 
of trench (this is the squad length, 1 yard per man and 1% feet at 
each end for traverse) with a corporal in charge of each squad. 
The corporal is held responsible for the men and work performed. 
To place a detachment on the work, the organization comprising it 
approaches the tools in column of files, rifles slung, pass between the 
piles of tools, shovels on the right, picks on the left. Engineer 
soldiers at each pile hand tools to the men as they pass. The cor- 
poral or squad leader places himself alongside the rear file of his 
squad, he takes a shovel while the file on his side takes a pick. 
Each squad leader then conducts his squad in column of files to the 
rear of the portion of the trench to be constructed by his squad. 
He usually halts his squad about 3 yards in rear of the cutting line 
and parallel to it. Work is started at the command: Commence 
work! The work should be divided into 2-hour tasks for each man. 
Weather conditions must at all times be taken in consideration. 
There should be one-sixth more men than theoretically required. 
Assuming men at 5-foot intervals and neglecting fractions the num- 
ber of hours required to dig a trench, is the section of trench in 
square feet divided by 5 for easy; 4 for medium, and 2! for hard 
soil. 

The table below gives the amount of work that can be accom- 
plished in one hour by one man: 


EXCAVATION— 
In easy soil— 
First, hoturcta.d 6s VPS SSP Rs es ee ee cubic feet, 30 
Second Hotri .) cong bike hae ee eae eta cubic feet, 25 
Third ‘hour 76, 3 ses sees oe cies sd ee ee cubic feet, 15 
Thereafter contmuotis work....). 220.2. eee ee cubic feet, 10 


in hard soil, about half the above. 
In loose earth, 60 cubic feet. 
Filling sand bags, 20 bags (0.5 cubic foot each). 


REVETMENT CONSTRUCTION (Material and tools on hand)— 


Rough brush woodsor, plank ye. ao. eae es sq. ft. per man, hour, 40 
Brushwood hurdles, rough— 
Making vee OR eeOnG storie eee ce ee ne meee sq. ft. per man, hour, 15 
Placing 3220) Pio Mee NOs aR a eae sq. ft. per man, hour, 30 
Sand bags— 
Pilling cat. aeeaihart wetagenios.c, eotae aie Ratt cutee sq. ft. per man, hour, 10 
Placing Give ic aa eter orleans en oe sq. ft. per man, hour, 20 
Sod— 
Obtaining SGe FOr cates oe der ules ee eee sq. ft. per man, hour, 7 . 
PIACing a ee ie eRe en See sq. ft. per man, hour, 10 
OBSTACLE CONSTRUCTION (Material and tools on hand)— 
Abattis, wired x1 strong tow) oJ. fe la tate ee eee linear feet, 1.5 
Wire entanglement— 
High | ites tad 258 sh cee fe ner ed Ga eens square feet, 27 
LOW sss oho eee eke, oe Sel ti ap Shane od ete aera square feet, 90 


By working in two reliefs above figures can be increased by one-third. 


26 


Ss 


CLEARING— 


Bmickets up tod.5)inches diameter... 2. cl.s.. seh oe. square yards, 25 
Light clearing of soft woods, trees to 12 in. in diameter.square yards, 25 
MMTENENL.) CLOT AST Pid. titre Sifet Mates lsd acbiaia ca ah «o's vee square yards, 15 


Plate 13 shows in outline the general method of laying out 
and proceeding with the work. 


OBSERVATION, TELEPHONE, WATER SUPPLY AND MAGAZINES. 


‘Well concealed and well located observation stations are very 
necessary for a fortified position. These stations must afford the 
observer a maximum amount of cover and concealment, consistent 
with the performance of his duties. 

A complete telephone system is necessary so as to afford ready 
communication with all parts of the fortified position. With a com- 





te 


Picks BHOVELS 


ULL i 


ENGINEER SOLDIER 


\ 
eee ae ee oe eee ey eee ee Mind ae ef Picea) Neen QUARTERS 


igen ts: 


\ 
| 
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A 
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plete telephone system, guns of the same batteries can be scattered 
over considerable area without the loss of fire control. 

Good drinking water must be provided for the soldiers who 
occupy the trenches. Clean water is also a help for the “‘first aid” 
of the wounded. The arrangement to be made will depend on the 
local requirements and conditions. 

Special magazines are not necessary. Recesses cut in front 
wall or cartridge boxes placed at convenient places will generally 
fulfil the requirements of ammunition storage. 


27 


Sk La ee Td AD oe! aE! FRY SM ARARE Met ite iy Bee TGA an REE eae nen 
Nae 


A GERMAN FORTIFIED POSITION. 


Major General Mayer proposes the following arrangement of a 
defensive position: As he considers that observation from aero- 
planes may obviate the difficulty of locating the exact position of 
the defenders’ shelter trenches, and he thinks a distinct difference 
should obtain in the defense against distant fire and against the close 
attack and assault. He constructs an advanced line of fire trenches 
for defense against the close attack and 100 meters behind this a 
second row of cover trenches, connected by approaches with the 
front line. Both are dug out on the front slope of a hill below the 
crest, the rear or cover trench being about 200 meters in front of 
the line of guns just behind the crest. He proposes to have no wire 
entanglements as obstacles because these would be easily seen and 
give away the position; but to have land-mines constructed 150 
meters in front of the front fire-trenches. Machine gun sections 
should deliver frontal and oblique fire between the land-mines and 
the front line of fire-trenches to meet the close attack. Also 
machine guns for more distant frontal fire effect should be in posi- 
tion behind the line of cover-trenches. Machine guns in pairs should 
also be placed for flanking fire in or behind the shelter-trench for 
the close defense. This system cannot be spoken of as multiplying 
the defensive lines. It is a single line, if you consider that the second 
trench is simply a line of trenches arranged as a cover-trench for 
defense from distant fire. The designer pictures to himself the 
course of the action thus: The airmen have from their great height 
only been able to observe the ground very generally. The machine 
guns being easily masked, would remain unnoticed. The guns and 
rear line of machine guns open fire, say, at 1,500 meters, against the 
hostile infantry advancing cautiously to the attack. The line of 
defenders told off for distant fire would only open fire when the 
attackers reinforce strongly, then they use rapid fire. No shot is 
fired out of the front fire-trenches until the attackers come within 
300 yards. Then the machine guns in the front line open fire and 
oblige the attackers to bring up field-guns to engage them. The men 
in the front shelter-trench fire open fire when the attackers are 
about 150 meters off and the mines have begun to act. This would 
be the moment for the counter-stroke by the reserve, which has 
been kept back concealed. The decisive line of defense is thus 
undiscovered until the decisive moment, which the defender utilizes 
to repulse the attack. 


BRITISH TRENCHES. 


The following remarks are extracted from Instructions in 
Field Training for the British Army. They are based upon the 
experience of the European War. They are especially applicable 
to fortifications which are to be occupied for a relatively long time 
and in relatively close proximity to similar works of the enemy. 
They are also of special interest as indications of the very great 


28 


power of modern weapons and the resulting necessity for conceal- 
ment from view: 


Trenches should be located so that they are not under observa- 
tion by hostile artillery. Possible observing stations on ground 
occupied by the enemy should also be considered. This conceal- 
ment is regarded as of greater importance than an extensive field 
of fire. | 

A field of fire of 100 yards will be sufficient if it cannot be 
extended without loss of concealment. Obstacles in front of the 
trenches must be carefully concealed, as otherwise they will assist 
the enemy to locate the trenches in rear. 

A location for the trenches back of a slight rise or back of a 
second hedge with obstacles hidden or entangled in the hedge in 
front has been found to afford satisfactory concealment. 

Modern artillery fire is practically continuous and the accuracy 
of ranging phenomenal. Accordingly, the target must be reduced 
to the smallest possible dimensions. This is best accomplished by 
making the trenches as narrow and as deep as possible with practi- 
cally no parapet. Support trenches especially should be made deep. 
The support trenches should be about 40 yards in rear of and 
parallel to the fire trenches with ample communications to the latter. 
To these most of the men retire during a bombardment, leaving as 
few as possible in the fire trenches. Eighteen to twenty-four inches 
is sufficient width for a trench. As this does not permit of the 
free passage of men along the trench, communication is secured by 
means of a narrow trench about 15 yards in rear of the firing 
trench and connected to the latter at each traverse by a narrow 
passage of the same depth. (See Plate 14.) 

The fire trenches should be of the recessed traversed type when- 
ever time permits, traverses about 5 feet wide at the base and 35 feet 
center to center. (See Plate 15.) 

Surplus earth from the trench excavation should be spread or 
sodded, depending on the nature of the soil. 

A bank of earth as a parados should be placed behind and close 
to the trenches for protection against the back blast of high ex- 
plosive shells, provided this can be done without rendering the 
trenches conspicuous. These parados should be sodded or other- 
wise concealed in the same manner as the parapet. Dummy para- 
pets may be constructed with surplus earth. 

Recesses under the parapet must be ceiled. If planking or 
other similar material is available time and trouble may be saved 
by laying the ceiling for the recesses on the ground at the front of 
the trench, with a good bearing at the ends, and then excavating 
the recess and throwing the earth on top of the ceiling to form 
the inner part of the parapet. The recesses serve to protect their 
occupants from shrapnel fire. 

Elbow rests should be omitted or made very narrow. Most of 
the men will prefer to make their own niches for the forearm. A 


29 


device to ensure proper aiming in the absence of lights during a 
night attack is desirable. 

Head cover and overhead cover are usually impracticable, ex- 
cept at points to be used as observing stations. They restrict the use 
of the rifle and bayonet. Where head cover can be constructed to 
advantage a continuous loophole is the best form. } 

The arrangement of trenches should be such as to develop as 
much frontal fire as possible. Attacks by the enemy usually occur 
at frequent intervals at night along the whole line. Under such 
conditions adjacent sections of the line can give but little support 
to each other by crossing fire. As cross and flanking fire is not to 
be relied upon, straight trenches are preferred. 


FuRING TRENCH 


= TRAVERSE 





GENERAL PLAN OF MODERN BRITISH TRENCHES 


Fig. 14. 


Dressing stations and latrine may be provided in recesses in the 
support trenches. 

Drainage should be considered in laying out the trenches. 
When practicable they should be drained to a low point in the 
locality. When this is not practicable, sump holes must be pro- 
vided in the trenches, to be pumped or baled out. 

Machine gun emplacement should be on the flanks of a section 
and as well concealed as possible. They should not be unmasked 
too soon, as this exposes them to premature desta by the 
hostile artillery. 

Cover required for the reserves will depend upon their distance 
in rear of the firing line and the enemy’s ability to search with fire 


30 


the ground in which the reserves are stationed. The possibility of 
observation by aerial reconnaisance must always be considered. 
Obstacles must be provided to check the enemy’s attempts to 
rush the trenches. Barbed wite is the most effective obstacle, 
especially if. well concealed. The advantage of concealment, in addi- 
tion to preventing the use of the obstacles as range marks for the 
trenches in rear, is that working parties are enabled to repair each 
night any damage to the obstacles. This repair work must fre- 
quently be carried out not over 100 yards and occasionally not over 
90 yards from the enemy’s trenchés. High wire entanglements 
involving the use of posts extending 3 feet 6 inches or 4 feet above 
the ground are impracticable owing to the difficulty of concealment 
and of repair. The driving of such posts is out of the question when 











DETAIL PLAN OF RECESSED AND TRAVERSED 
BRITISH FIRING TRENCH 


ENLARGED SECTION A-A 





Fig. 15. 


hostile trenches are in close proximity. Various substitutes for 
these posts may be employed, such as tripods, constructed of the 
limbs of trees lashed together, carried out and set in front of the 
firing line at night, at intervals of about 15 feet. The tripods are 
anchored to the ground and barbed wire laced between them. Any 
light, strong, portable support for barbed wire entanglements is 
‘acceptable. 
Flare lights shielded on the side of the defender may be 
~ employed. | 

If the flank of a line is refused, the trenches should be echeloned 
to the rear. Otherwise the trenches on the flank will be subject to 
enfilade fire, especially by heavy artillery at long ranges. 


31 


» 


The following observations of the aeronauts will be of assistance 
to those engaged in the construction of field fortifications: 

1. A long continuous line of trenches is more visible than 
groups of trenches. 

2. Straight trenches are conspicuous. 

3. Trenches across plowed fields are easily distinguished. 

4. Straw spread in the bottom of trenches renders them con- 
spicuous. 

5. Trenches against hedges cannot be distinguishable. 

6. It is difficult to tell whether trenches or gun emplacements 
are occupied. 

7. Tracks to emplacements are easily distinguished. 

8. Trenches should be covered with brush to hide deep 
shadows at bottom. 

9. The operations on the European battle fields: closely re- 
semble the methods which have hitherto been considered charac- 
teristic of sieges. 

Sir John French says: ‘In war as it is today, between civilized 
nations armed to the teeth with the present deadly rifle and machine 
gun, heavy casualties are absolutely unavoidable. For the slightest 
undue exposure the heaviest toll is exacted. The power of defense 
conferred by modern weapons is the main cause for the long dura- 
tion of the battles of the present day, and it is this fact which mainly 
accounts for such loss and waste of life. Both one and the other 
can, however, be shortened and lessened if attacks can be supported 
by a most efficient and powerful force of artillery available; but 
an almost unlimited supply of ammunition is necessary, and a most 
liberal discretionary power as to its use must be given to artillery 
commanders. I am confident that this is the only means by which 
great results can be obtained with a minimum of loss.” 


PERMANENT FORTIFICATION. 


The ease with which the Germans successfully captured Liege, 
Namur, Antwerp, and the camp retranches of Maubeuge, Lille, 
Laon-La Fere and Rheims, all very strong positions on paper, has 
proved rather damaging to the prestige of permanent fortifications. 
-Yet there is no case for a wholesale condemnation of forts when 
circumstances are carefully examined. Both Belgian and French 
fortresses were sadly out of date in armament as well as in defensive 
organization, and were crushed at long range by an artillery of 
superior caliber (280, 305 and 420: millimeters—11.032, 12.017 and 
15.548 inches) to which they could make no effective reply. To 
the admirably handled German heavy ordnance that fired with in- 
credible accuracy at ranges of ten to fourteen kilometers, the French 
fortress artillery could only oppose, together with obsolete mortars 
and insufficient field guns, weapons of 155 millimeters (6.107 inches) 
with a range of little over 8,000 yards. 

No attempt was made to defend Lille, Laon and Rheims, totally 
out of date and not thought to be worth the huge garrisons which 


32 


they would have absorbed. Maubeuge alone offered a stout resist- 
ance, though perhaps not so long as could have been expected from 
its new (but under-gunned) forts and from its garrison of 30,000 
men, including nine infantry regiments and a few artillery battalions, 
mostly reservists. That place-forte, besides having no long range 
cannon, was filled by tens of thousands of helpless Belgian refugees, 
mostly women and children, which constituted a source of weakness. 
After a ceaseless night and day bombardment, lasting from August 
23 to September 7, in the course of which the garrison did its duty, 
attacking continuously and inflicting over 20,000 casualties on the 
enemy (so much was admitted by German officers), the governor, 
Gen. Fournier, surrendered a town on fire, full of dead and wotinded, 
the forts of which were reduced to heaps of ruins. Only a few 
thousand men of the garrison succeeded in breaking through the 
lines of the besiegers. 

It is estimated that Maubeuge rendered considerable service in 
delaying for two weeks the advance of an important portion of the 
hostile artillery and in preventing the enemy using the most direct 
railway line from Liege to Paris. The same is true also of the 
obsolete fortress of Longwy, where 3,000 Frenchmen stopped for 
twenty-one days part of the Kronprinz’s army, winning war honors 
from the victor, and of the old (1874) fort of Troyon, with a 
garrison of 470 men, which the enemy was confident of reducing in 
a few hours, but which resisted an intense bombardment of five 
days, repulsed three brave attacks of German infantry, and cost 
nearly 2,000 casualties to the besiegers. 

But, of course, reliable information as to the value of thifea: 
tions can only be derived from a study of the way modern fortresses 
have stood the test of war. Now, the camps retranches of Verdun, 
Toul, Epinal and Belfort are the only ones that deserve at all to 
be called modern, having been the object of ceaseless improvements 
in recent years, though at the beginning of the war they were not 
quite up to date in armament, not having received the long range 
naval guns that now arm them. And it is a fact that they have up 
to the present defied the whole might of heavy German guns ‘and 
the repeated and well-led attacks of the masses of German infantry, 
especially Verdun, which is yet partly encircled, though at very 
long distance—over 20,000 yards. 

From reliable source we further learn that the excellent resist- 
ance offered by the Verdun fortifications is also due to the fact that 
many of the large guns were removed from their permanent em- 
placement and were then placd in concealed positions from which 
they could be readily moved in case the enemy discovered the 
position. 

Several semi-permanent emplacements are provided for each 
eun. 

The small circular fort, with its batteries, powder magazines 
-and garrison quarters crowded over a limited area is a thing of the 
past. The permanent fortification with mobile and concealed bat- 


33 


teries distributed over a large area, and well placed and concealed 
infantry intrenchment is and will be of great value. This is the 
opinion of some of our army engineers and some of the foreign 
military experts. | 

The author herewith sets forth the requirements and conditions 
which he believes are necessary to withstand successfully the attack 
of the present high power weapons: | 
Superiority of range and armament. 
Concealment and mobility of armament. 
Wide area of operation. 
4. A cleared area around site of fort. 


Seelt all BS 


ART RE EEN EAREA OR 
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MR ML DeTe KR 96 5 GR Ane orl AD, Ie AO Ree eas ei 
Fie. 16 Modeled after the sketches of the 
1g. 10. fortrass of Ossewetz | 


taken by Major Robert R. MeCormiek 
5. Well placed and concealed obstacles. 
6. New type armored turrets. 
7. Dummy turrets. 
8. Concealed infantry trenches. 
9. Centrally located magazines. 
0 
1 


Cover for garrison. 
‘Covered and concealed communications between the differ- 


ent parts of the fort. 
12. A.complete telephone and wireless system. 
13. A complete lighting system. 


14. Ample water supply. 
Plates 16 and 17 will give a general idea of the author’s plan 


34 A 


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35 


of a modern permanent fortification. As to the thickness of cover, 
lighting system and other exact data and details we must await the 
further developments of this present war. 


SEA-COAST FORTIFICATION. 


General Bernard, in one of his reports, outlined the use and 
purpose of seacoast fortifications as follows: 

“Seacoast fortifications must close all important harbors against 
an enemy and secure them to our commercial and military marine. 

“Second, must deprive the enemy of all strong positions, where, 
protected by naval superiority, he might fix permanent quarters on 
our territory, maintain himself during the war and keep the whole 
frontier or coast in perpetual alarm. 

“Third, must cover the great cities from attack. 

yee ourth, must prevent, as far as practicable, the great avenues 
of interior navigation from being blockaded at their entrances into 
the ocean. 

“Fifth, must cover the coastwise and interior navigation by 
closing the harbors and the several inlets from the sea which inter- 
sect the lines of communication, and thereby further aid the navy 
in protecting the navigation of the country. 

“Sixth, they must protect the great naval establishments.” 

Wars of recent years, as well as the present European War, 
have demonstrated that it is practically impossible to reduce seacoast 
fortification, if properly defended, by ships’ fire, and, when fortified 
posts have fallen, such a result has been secured by land operation 
assisted by a blockade. The proper land defense in connection with 
coast defense is therefore an absolute necessity. 

An effective. system of coast defense must consist of land 
batteries, with their protecting guns and searchlights, submarine 
mines, torpedoes, torpedo and submarine boats, floating defenses, 
barricades, dams and proper land defenses. 

To prevent distant bombardment by a fleet, and also to prevent 
the forcing of a passage or a running past the defenses, high-power 
guns are required for disabling or silencing battleships and cruisers 
at long ranges, and in addition to the mines smaller guns of the 
rapid-fire type are needed for similar purposes and to repel torpedo- 
boat attacks at the closer ranges. 

Sea-coast fortifications are best protected from the attack from 
the land side by mobile troops well entrenched and supported by 
sufficient mobile artillery. The heavy guns and mortars should also 
be designed so that they can be turned and used in the land defense. 

Mines are and should be considered as obstacles and in order 
to accomplish their object must succeed in holding the enemy in 
the zone of greatest effective fire. They must allow safe passage 
of the vessels of the defense but must be instantly dangerous to 
the enemy’s ships. 

The United States coast defense is provided with 8-inch, 10-inch, 
12-inch and 16-inch caliber guns for heavy armament. The mortars 


36 


are mostly of 12-inch caliber. The rapid-fire armament consists of 
6-pounders and 15-pounders and 5-inch and 6-inch caliber guns. 

The long range guns are usually placed at a height of 165 to 
250 feet above sea-level. 


The mortars are usually placed at a height of 260 to 300 feet 
above sea-level. 


The lighter and rapid fire guns are usually placed at height of 
about 60 feet above sea-level. 

Three systems of range finding are now in use: 

1. The horizontal base system with a horizontal base along 
shore and which has an observation station at each end of this base. 
The target is located by the intersection of the lines of sight from 
the two stations. 

2. The vertical base system with the vertical height of instru- 
ment above mean low water as the vertical base. The distance to 


3OTosOVYos 


150 TOGOOYDS 


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A 
Y) 
j 
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Fi REDAN With CURTAIN 
Counten- & 
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SOUNTER-SCARF 
ERY 


CREMAILLERE 


Tae? aN 6ooTe 1200VOs4 


FIELD WORKS in COMBINATION 


a ne 





BASTIONES FORT 
Hes 


Fig. 18. 


the target is read off the instrument in yards directly when the 
horizontal cross-wires of the telescope is directed on the water line 
of the target. The azimuth is obtained on the graduated horizontal 
circle. 

3. The third system is the coincidence range-finding system, 
which requires a single station equipped with a coincidence range 
finder. This range finder is equipped with an azimuth reading 
device. 

For protection and cover, some of our sea-coast fortifications 
are provided with 15 feet of concrete and 45 feet of sand for walls 
exposed to horizontal fire and 10 feet of concrete where exposed to 
vertical fire. 

Mobility and concealment of armament should receive special 


37 


attention in modern fortification. Some of the large European, 
fortresses are equipped with heavy mobile armament and which 1s 
protected with steel cupolas. 

Conditions for good mine locations are shallow water and 
gentle current. A depth of about 100 feet and a current of about 
7 feet per second are the respective limits. 

Excessive tide ranges (over 10 feet) require a double system 
of mines; one in front for low water and another in rear for high 
water. The mines should be laid checker-board fashion with in- 
tervals not greater than 60 feet. 

Electric contact mines are generally used in coast-defense -with 
their cables connected to the firing station on shore. All mine fields 








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should be protected by rapid fire guns usually placed on the flanks 
of the mine field. 

Two examples of effective sea-coast fortification of the present 
European War are the fortifications of the Dardanelles and the 
fortifications of the Island of Helgoland. The fortifications of the 
Dardanelles have successfully withstood the combined naval and 
land attack and have inflicted severe losses on the enemy, both in 
ships and men. The fortification of the Island of Helgoland may 
be classed as the greatest military engineering work of this age. A 


38 


small barren and rock-strewn island has been transformed into a 
formidable defensive work and so well has the work been planned 
that Germany’s entire navy finds absolute protection behind this 
island, against the attack of the greatest navy that has ever cruised 
the waters of the world. 

To illustrate a modern fortified harbor, the system of the 
Austrian, Colonel Mielichhofer, is reproduced in Plate 19. 

The surrounding country of this harbor rises to 60 meters 
above sea-level, which permits of easy fortification. The inner 
harbor. allows of the location of arsenals and magazines which are 
entirely covered by the heights, so that these works are not only 
protected from bombardment by distance, but also by their position. 
The inner harbor is of sufficient area to accommodate the entire 


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u.S. COAST-OEFENCE FORTIFICATION 


Bie 20. 


fleet. The harbor entrance is quite narrow and easily obstructed, 
thus making it very easy to defend. | 

There are two mine fields provided—an outer and an inner. 
The outer mines surround the entrance proper at a distance of 
about 2,000 yards and this mine zone is located in the most effective 
zone of fire of the heavy coast guns. The mines are located and 
arranged in a double row. The mines nearest to shore are judg- 
ment mines, which permit the vessels of the defense to pass over 
them uninjured, while the others are contact mines. 

The inner obstructions consist of a submarine dam at the center 
of the entrance with passages at each end which are closed by judg- 
ment mines. In rear of these mines barricades are placed. 

The mine fields and barricades are flanked by rapid fire batteries 


39 


and shore torpedo batteries. The field of fire is illuminated by means 
of searchlights. | 
Plate 20 shows a typical sea-coast fortification in detail. 


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THE GERMAN MOVABLE TURRET 


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TURRET TORTS 


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Fig. 21. 


Plate No. 21 shows a Belgian steel turret fort; also a German 
portable turret. These steel turrets are usually placed in combina- 
tion with trenches as outlined in plan on this plate? 


40 











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